Memories that support reconfigurable logic LSIs have been demanded as computers become more diversified and faster. As such memories, non-volatile memories are desirable, not volatile memories such as DRAM (Dynamic Random Access Memory). At present, EEPROMs (Electronically Erasable and Programmable Read Only Memories), flash memories, and the like are used as non-volatile memories. Yet, there is a need for a fast, large-capacity, low power consumption memory that supports recording and reproducing with a higher degree of freedom, and the development of new memories such as FeRAMs (Ferroelectric Random Access Memories) and MRAMs (Magnetoresistive Random Access Memories) has been actively pursued. As one type of such new memories, RRAMs (Resistance Random Access Memories) have been expected to be a promising low-power consumption, high-speed memory.
The RRAM is a non-volatile memory that uses a CMR (Colossal Magnetoresistance) thin film as a storage element and performs recording and reproducing of information utilizing an electric resistance change in the CMR film caused by applying a pulse voltage to the CMR film (see, for example, U.S. Pat. Nos. 6,204,139 and 6,473,332).
RRAMs have the following two major problems. One is that the applied voltage (drive voltage) is high. Under the current state of the art, the voltage of electric pulse to be applied is about 5 V. However, reduction in the voltage is essential to increase the device speed and lower the power consumption. Another is large variations in the resistance of the thin film after the electric pulse application, in other words, large variations in the pulse width (duration) of the electric pulse required to achieve a given resistance change. In particular, variations in the pulse width are large when a polycrystalline film is used as the CMR thin film.